The Reference scenario and the Energy [R]evolution scenario are based on the same projections of population and economic development.
The future development of energy intensity, however, differs between the reference and the alternative case, taking into account the measures to increase energy efficiency under the Energy [R]evolution scenario.

future investments in the heat sector

Also in the heat sector the Energy [R]evolution scenario would require a major revision of current investment strategies in heating technologies. Especially the not yet so common solar and geothermal and heat pump technologies need enourmous increase in installations, if these potentials are to be tapped for the heat sector. Installed capacity needs to increase from today 19 GW to more than 2000 GW for solar thermal and from 2 GW to more than 1400 GW for geothermal and heat pumps. Capacity of biomass technologies, which are already rather wide spread will decrease by more than 50% due to the limited availability of sustainable biomass.

Renewable heating technologies are extremely variable, from low tech biomass stoves and unglazed solar collectors to very sophisticated enhanced geothermal systems and solar thermal district heating plants with seasonal storage. Thus it can only roughly be calculated, that the Energy [R]evolution scenario in total requires around $ 6,300 billion to be invested in renewable heating technologies until 2050 (including investments for replacement after the economic lifetime of the plants) - approximately $ 160 billion per year.”